Most of us have probably experienced that awkward clash of teeth or turned our heads the wrong way when going in for a smooch, making it a pretty un-sexy experience.

But when it comes to our body’s reaction to kissing someone for the first time, there’s definitely a lot of chemistry going on — particularly in our saliva, reports The Sun.

There’s actually a whole field of study dedicated to the impact that puckering up has on us — philematology, known as the science of kissing.

Here we take a look at the incredible things that happen to your body when you lock lips.

OUR SALIVA WORKS OVERTIME

There are several very interesting theories about our saliva and its role in kissing — both of which hark back the theory of evolution.

One states that a sloppy smooch is our body’s way of sizing up whether the person we’re kissing is a potential “mate.”

According to research conducted by Oxford University, the chemical makeup of saliva helps your body to decide whether the person you’re exchanging it with would produce strong offspring.

Another states that men prefer a more saliva-tastic, slobbery kiss.

The reason for this, according to Helen Fisher from Rutger’s University in New Jersey is that men’s saliva contains more testosterone.

As a result, when they kiss a partner they are unconsciously passing on their slobber in an attempt to activate the part of the woman’s brain associated with sex drive.

IT RELEASES THE LOVE HORMONE

When we engage in any kind of sexual activity, our body releases oxytocin from the pituitary gland.

This makes us feel more aroused and can also help to generate a closer bond and trust with our kissing partner.

Kissing sends our oxytocin levels through the roof, so it helps to bring people closer together in more ways than one.

IT HELPS FIGHT CHOLESTEROL

Apparently, smooching can have a positive impact on your blood lipid levels.

Romantic kissing can actually decrease serum cholesterol and increase overall relationship satisfaction for couples, according to researchers for the Western Journal of Communication.

IT HELPS US TO DE-STRESS

Feeling wound up after a trying day at work? Pucker up.

One study found university students who took part in 15-minute kissing sessions dramatically decreased their levels of the stress hormone cortisol, reports NBC.

Male participants also experienced a rise in oxytocin — however in this instance females saw a decrease.

YOU GET A WORK-OUT — IF IT’S A LONG ONE

A passionate kiss is said to burn around 6.4 calories a minute.

This means that a half-hour kissing session burns the same amount of calories as running for 25 minutes or swimming for half an hour, depending on your fitness levels.

IT TONES UP FACIAL MUSCLES

Kissing can even be great for prolonging your youthful looks!

Depending on your “style,” you use around 30 muscles when you kiss.

Repeatedly locking lips tones up the muscles in your face, preventing them from drooping.

OUR PUPILS WIDEN

This is the reason why we tend to close our eyes when we pucker up!

PHEROMONES ARE ON THE LOOSE

This theory is better documented in animals, but the idea is that pheromones, which are similar to hormones, are released outside of the body when we kiss.

Apparently our partner can sense them with their nose and mouth, and this helps them to detect whether or not you are aroused.

Can Hugs Help Keep You Healthy?0:52

Mounting scientific evidence seems to suggest that hugs are good for your health. They lower blood pressure which is a risk factor for heart disease. Oxytocin, the chemical released by the brain while hugging, is being investigated as a treatment for various conditions, including depression.